I like the way people guess what is possible and what's available just by readyng reviews on the web.
I belive ATI and other vendors as well can do anything they want with memory configuration. 128bit wide bus allows lot's of memory. they just have to use different memory chips, assuming that the memory controler is flexible enough.
my guess is that they had such a good yield on r300, that they decided it would be a waste of time designing and testing different PCBs. they much rathered differentiating the cards by using resistors and more or less memory modules.
This way, they can use most of the chips manufactured for the model that's selling best.
the 9500Pro is the exception with a unique PCB hence it's late and unavailable.
If, in the following weeks vendors decide to put an end to the Hacking fiesta, they can start making 9500 128mb cards with 128bit buses like the 9500Pro, or a thousand other creative solutions that smarter people than me can come up with.
new designs with the same brand names will cause a great deal of confusion to the people looking for the hackable cards.
but, I don't believe vendors will slow down their factories just so that a few soldering geeks won't get performance they didn't pay for.
the vast majority of people don't have a clue it's possible, and others wouldn't dream of doing it.
Lastly, another guess of mine would be that comparable performance will be available for the same prices within 4 months so why bother with a new PCB ?